cleaning up the slant six head

Personally I'd just gasket match the intakes down 3/4"-1" into the port and leave a small step on the exhausts.
Thanks for the other tips, I will add them to what I need to look into.

Can you explain further what you mean here though, give me more details.

It sounds simple enough that I should be able to grasp what you suggest but being a novice at this sort of thing leaves me still a bit confused and looking for details.